Create a subpackage for utils

utils/utils.go

@@ -0,0 +1,470 @@
+package utils
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"index/suffixarray"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Go is a basic promise implementation: it wraps calls a function in a goroutine,
+// and returns a channel which will later return the function's return value.
+func Go(f func() error) chan error {
+	ch := make(chan error)
+	go func() {
+		ch <- f()
+	}()
+	return ch
+}
+
+// Request a given URL and return an io.Reader
+func Download(url string, stderr io.Writer) (*http.Response, error) {
+	var resp *http.Response
+	var err error = nil
+	if resp, err = http.Get(url); err != nil {
+		return nil, err
+	}
+	if resp.StatusCode >= 400 {
+		return nil, errors.New("Got HTTP status code >= 400: " + resp.Status)
+	}
+	return resp, nil
+}
+
+// Debug function, if the debug flag is set, then display. Do nothing otherwise
+// If Docker is in damon mode, also send the debug info on the socket
+func Debugf(format string, a ...interface{}) {
+	if os.Getenv("DEBUG") != "" {
+
+		// Retrieve the stack infos
+		_, file, line, ok := runtime.Caller(1)
+		if !ok {
+			file = "<unknown>"
+			line = -1
+		} else {
+			file = file[strings.LastIndex(file, "/")+1:]
+		}
+
+		fmt.Fprintf(os.Stderr, fmt.Sprintf("[debug] %s:%d %s\n", file, line, format), a...)
+	}
+}
+
+// Reader with progress bar
+type progressReader struct {
+	reader       io.ReadCloser // Stream to read from
+	output       io.Writer     // Where to send progress bar to
+	readTotal    int           // Expected stream length (bytes)
+	readProgress int           // How much has been read so far (bytes)
+	lastUpdate   int           // How many bytes read at least update
+	template     string        // Template to print. Default "%v/%v (%v)"
+}
+
+func (r *progressReader) Read(p []byte) (n int, err error) {
+	read, err := io.ReadCloser(r.reader).Read(p)
+	r.readProgress += read
+
+	updateEvery := 4096
+	if r.readTotal > 0 {
+		// Only update progress for every 1% read
+		if increment := int(0.01 * float64(r.readTotal)); increment > updateEvery {
+			updateEvery = increment
+		}
+	}
+	if r.readProgress-r.lastUpdate > updateEvery || err != nil {
+		if r.readTotal > 0 {
+			fmt.Fprintf(r.output, r.template+"\r", r.readProgress, r.readTotal, fmt.Sprintf("%.0f%%", float64(r.readProgress)/float64(r.readTotal)*100))
+		} else {
+			fmt.Fprintf(r.output, r.template+"\r", r.readProgress, "?", "n/a")
+		}
+		r.lastUpdate = r.readProgress
+	}
+	// Send newline when complete
+	if err != nil {
+		fmt.Fprintf(r.output, "\n")
+	}
+
+	return read, err
+}
+func (r *progressReader) Close() error {
+	return io.ReadCloser(r.reader).Close()
+}
+func ProgressReader(r io.ReadCloser, size int, output io.Writer, template string) *progressReader {
+	if template == "" {
+		template = "%v/%v (%v)"
+	}
+	return &progressReader{r, output, size, 0, 0, template}
+}
+
+// HumanDuration returns a human-readable approximation of a duration
+// (eg. "About a minute", "4 hours ago", etc.)
+func HumanDuration(d time.Duration) string {
+	if seconds := int(d.Seconds()); seconds < 1 {
+		return "Less than a second"
+	} else if seconds < 60 {
+		return fmt.Sprintf("%d seconds", seconds)
+	} else if minutes := int(d.Minutes()); minutes == 1 {
+		return "About a minute"
+	} else if minutes < 60 {
+		return fmt.Sprintf("%d minutes", minutes)
+	} else if hours := int(d.Hours()); hours == 1 {
+		return "About an hour"
+	} else if hours < 48 {
+		return fmt.Sprintf("%d hours", hours)
+	} else if hours < 24*7*2 {
+		return fmt.Sprintf("%d days", hours/24)
+	} else if hours < 24*30*3 {
+		return fmt.Sprintf("%d weeks", hours/24/7)
+	} else if hours < 24*365*2 {
+		return fmt.Sprintf("%d months", hours/24/30)
+	}
+	return fmt.Sprintf("%d years", d.Hours()/24/365)
+}
+
+func Trunc(s string, maxlen int) string {
+	if len(s) <= maxlen {
+		return s
+	}
+	return s[:maxlen]
+}
+
+// Figure out the absolute path of our own binary
+func SelfPath() string {
+	path, err := exec.LookPath(os.Args[0])
+	if err != nil {
+		panic(err)
+	}
+	path, err = filepath.Abs(path)
+	if err != nil {
+		panic(err)
+	}
+	return path
+}
+
+type nopWriter struct {
+}
+
+func (w *nopWriter) Write(buf []byte) (int, error) {
+	return len(buf), nil
+}
+
+type nopWriteCloser struct {
+	io.Writer
+}
+
+func (w *nopWriteCloser) Close() error { return nil }
+
+func NopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w}
+}
+
+type bufReader struct {
+	buf    *bytes.Buffer
+	reader io.Reader
+	err    error
+	l      sync.Mutex
+	wait   sync.Cond
+}
+
+func NewBufReader(r io.Reader) *bufReader {
+	reader := &bufReader{
+		buf:    &bytes.Buffer{},
+		reader: r,
+	}
+	reader.wait.L = &reader.l
+	go reader.drain()
+	return reader
+}
+
+func (r *bufReader) drain() {
+	buf := make([]byte, 1024)
+	for {
+		n, err := r.reader.Read(buf)
+		r.l.Lock()
+		if err != nil {
+			r.err = err
+		} else {
+			r.buf.Write(buf[0:n])
+		}
+		r.wait.Signal()
+		r.l.Unlock()
+		if err != nil {
+			break
+		}
+	}
+}
+
+func (r *bufReader) Read(p []byte) (n int, err error) {
+	r.l.Lock()
+	defer r.l.Unlock()
+	for {
+		n, err = r.buf.Read(p)
+		if n > 0 {
+			return n, err
+		}
+		if r.err != nil {
+			return 0, r.err
+		}
+		r.wait.Wait()
+	}
+	panic("unreachable")
+}
+
+func (r *bufReader) Close() error {
+	closer, ok := r.reader.(io.ReadCloser)
+	if !ok {
+		return nil
+	}
+	return closer.Close()
+}
+
+type WriteBroadcaster struct {
+	mu      sync.Mutex
+	writers map[io.WriteCloser]struct{}
+}
+
+func (w *WriteBroadcaster) AddWriter(writer io.WriteCloser) {
+	w.mu.Lock()
+	w.writers[writer] = struct{}{}
+	w.mu.Unlock()
+}
+
+// FIXME: Is that function used?
+// FIXME: This relies on the concrete writer type used having equality operator
+func (w *WriteBroadcaster) RemoveWriter(writer io.WriteCloser) {
+	w.mu.Lock()
+	delete(w.writers, writer)
+	w.mu.Unlock()
+}
+
+func (w *WriteBroadcaster) Write(p []byte) (n int, err error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	for writer := range w.writers {
+		if n, err := writer.Write(p); err != nil || n != len(p) {
+			// On error, evict the writer
+			delete(w.writers, writer)
+		}
+	}
+	return len(p), nil
+}
+
+func (w *WriteBroadcaster) CloseWriters() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	for writer := range w.writers {
+		writer.Close()
+	}
+	w.writers = make(map[io.WriteCloser]struct{})
+	return nil
+}
+
+func NewWriteBroadcaster() *WriteBroadcaster {
+	return &WriteBroadcaster{writers: make(map[io.WriteCloser]struct{})}
+}
+
+func GetTotalUsedFds() int {
+	if fds, err := ioutil.ReadDir(fmt.Sprintf("/proc/%d/fd", os.Getpid())); err != nil {
+		Debugf("Error opening /proc/%d/fd: %s", os.Getpid(), err)
+	} else {
+		return len(fds)
+	}
+	return -1
+}
+
+// TruncIndex allows the retrieval of string identifiers by any of their unique prefixes.
+// This is used to retrieve image and container IDs by more convenient shorthand prefixes.
+type TruncIndex struct {
+	index *suffixarray.Index
+	ids   map[string]bool
+	bytes []byte
+}
+
+func NewTruncIndex() *TruncIndex {
+	return &TruncIndex{
+		index: suffixarray.New([]byte{' '}),
+		ids:   make(map[string]bool),
+		bytes: []byte{' '},
+	}
+}
+
+func (idx *TruncIndex) Add(id string) error {
+	if strings.Contains(id, " ") {
+		return fmt.Errorf("Illegal character: ' '")
+	}
+	if _, exists := idx.ids[id]; exists {
+		return fmt.Errorf("Id already exists: %s", id)
+	}
+	idx.ids[id] = true
+	idx.bytes = append(idx.bytes, []byte(id+" ")...)
+	idx.index = suffixarray.New(idx.bytes)
+	return nil
+}
+
+func (idx *TruncIndex) Delete(id string) error {
+	if _, exists := idx.ids[id]; !exists {
+		return fmt.Errorf("No such id: %s", id)
+	}
+	before, after, err := idx.lookup(id)
+	if err != nil {
+		return err
+	}
+	delete(idx.ids, id)
+	idx.bytes = append(idx.bytes[:before], idx.bytes[after:]...)
+	idx.index = suffixarray.New(idx.bytes)
+	return nil
+}
+
+func (idx *TruncIndex) lookup(s string) (int, int, error) {
+	offsets := idx.index.Lookup([]byte(" "+s), -1)
+	//log.Printf("lookup(%s): %v (index bytes: '%s')\n", s, offsets, idx.index.Bytes())
+	if offsets == nil || len(offsets) == 0 || len(offsets) > 1 {
+		return -1, -1, fmt.Errorf("No such id: %s", s)
+	}
+	offsetBefore := offsets[0] + 1
+	offsetAfter := offsetBefore + strings.Index(string(idx.bytes[offsetBefore:]), " ")
+	return offsetBefore, offsetAfter, nil
+}
+
+func (idx *TruncIndex) Get(s string) (string, error) {
+	before, after, err := idx.lookup(s)
+	//log.Printf("Get(%s) bytes=|%s| before=|%d| after=|%d|\n", s, idx.bytes, before, after)
+	if err != nil {
+		return "", err
+	}
+	return string(idx.bytes[before:after]), err
+}
+
+// TruncateId returns a shorthand version of a string identifier for convenience.
+// A collision with other shorthands is very unlikely, but possible.
+// In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
+// will need to use a langer prefix, or the full-length Id.
+func TruncateId(id string) string {
+	shortLen := 12
+	if len(id) < shortLen {
+		shortLen = len(id)
+	}
+	return id[:shortLen]
+}
+
+// Code c/c from io.Copy() modified to handle escape sequence
+func CopyEscapable(dst io.Writer, src io.ReadCloser) (written int64, err error) {
+	buf := make([]byte, 32*1024)
+	for {
+		nr, er := src.Read(buf)
+		if nr > 0 {
+			// ---- Docker addition
+			// char 16 is C-p
+			if nr == 1 && buf[0] == 16 {
+				nr, er = src.Read(buf)
+				// char 17 is C-q
+				if nr == 1 && buf[0] == 17 {
+					if err := src.Close(); err != nil {
+						return 0, err
+					}
+					return 0, io.EOF
+				}
+			}
+			// ---- End of docker
+			nw, ew := dst.Write(buf[0:nr])
+			if nw > 0 {
+				written += int64(nw)
+			}
+			if ew != nil {
+				err = ew
+				break
+			}
+			if nr != nw {
+				err = io.ErrShortWrite
+				break
+			}
+		}
+		if er == io.EOF {
+			break
+		}
+		if er != nil {
+			err = er
+			break
+		}
+	}
+	return written, err
+}
+
+func HashData(src io.Reader) (string, error) {
+	h := sha256.New()
+	if _, err := io.Copy(h, src); err != nil {
+		return "", err
+	}
+	return "sha256:" + hex.EncodeToString(h.Sum(nil)), nil
+}
+
+type KernelVersionInfo struct {
+	Kernel int
+	Major  int
+	Minor  int
+	Flavor string
+}
+
+func (k *KernelVersionInfo) String() string {
+	flavor := ""
+	if len(k.Flavor) > 0 {
+		flavor = fmt.Sprintf("-%s", k.Flavor)
+	}
+	return fmt.Sprintf("%d.%d.%d%s", k.Kernel, k.Major, k.Minor, flavor)
+}
+
+// Compare two KernelVersionInfo struct.
+// Returns -1 if a < b, = if a == b, 1 it a > b
+func CompareKernelVersion(a, b *KernelVersionInfo) int {
+	if a.Kernel < b.Kernel {
+		return -1
+	} else if a.Kernel > b.Kernel {
+		return 1
+	}
+
+	if a.Major < b.Major {
+		return -1
+	} else if a.Major > b.Major {
+		return 1
+	}
+
+	if a.Minor < b.Minor {
+		return -1
+	} else if a.Minor > b.Minor {
+		return 1
+	}
+
+	return 0
+}
+
+func FindCgroupMountpoint(cgroupType string) (string, error) {
+	output, err := ioutil.ReadFile("/proc/mounts")
+	if err != nil {
+		return "", err
+	}
+
+	// /proc/mounts has 6 fields per line, one mount per line, e.g.
+	// cgroup /sys/fs/cgroup/devices cgroup rw,relatime,devices 0 0
+	for _, line := range strings.Split(string(output), "\n") {
+		parts := strings.Split(line, " ")
+		if len(parts) == 6 && parts[2] == "cgroup" {
+			for _, opt := range strings.Split(parts[3], ",") {
+				if opt == cgroupType {
+					return parts[1], nil
+				}
+			}
+		}
+	}
+
+	return "", fmt.Errorf("cgroup mountpoint not found for %s", cgroupType)
+}